IPHONE: Fall back to CLUT8 in case a non-supported screen mode is set up.

This makes the iPhone backend conform with the 16bpp API and thus no longer
causes assertions to fail in case the client code tries to set up an
unsupported game screen format.

3 files changed, 13 insertions, 4 deletions

diff --git a/backends/platform/iphone/osys_main.cpp b/backends/platform/iphone/osys_main.cpp
index f3e0d97b97..9a33cd8968 100644
--- a/backends/platform/iphone/osys_main.cpp
+++ b/backends/platform/iphone/osys_main.cpp
@@ -60,7 +60,7 @@ OSystem_IPHONE::OSystem_IPHONE() :
 	_screenOrientation(kScreenOrientationFlippedLandscape), _mouseClickAndDragEnabled(false),
 	_gestureStartX(-1), _gestureStartY(-1), _fullScreenIsDirty(false), _fullScreenOverlayIsDirty(false),
 	_mouseDirty(false), _timeSuspended(0), _lastDragPosX(-1), _lastDragPosY(-1), _screenChangeCount(0),
-	_mouseCursorPaletteEnabled(false) {
+	_mouseCursorPaletteEnabled(false), _gfxTransactionError(kTransactionSuccess) {
 	_queuedInputEvent.type = Common::EVENT_INVALID;
 	_touchpadModeEnabled = !iPhone_isHighResDevice();
 	_fsFactory = new POSIXFilesystemFactory();
diff --git a/backends/platform/iphone/osys_main.h b/backends/platform/iphone/osys_main.h
index 5d0f60c34c..b443e22f56 100644
--- a/backends/platform/iphone/osys_main.h
+++ b/backends/platform/iphone/osys_main.h
@@ -65,6 +65,9 @@ protected:
 
 	Graphics::Surface _framebuffer;
 
+	// For signaling that screen format set up might have failed.
+	TransactionError _gfxTransactionError;
+
 	// For use with the game texture
 	uint16  _gamePalette[256];
 	// For use with the mouse texture
diff --git a/backends/platform/iphone/osys_video.mm b/backends/platform/iphone/osys_video.mm
index 2b5e78bd35..6f80a6cba3 100644
--- a/backends/platform/iphone/osys_video.mm
+++ b/backends/platform/iphone/osys_video.mm
@@ -84,6 +84,13 @@ void OSystem_IPHONE::initSize(uint width, uint height, const Graphics::PixelForm
 	// to the texture buffer to avoid an additional copy step.
 	[g_iPhoneViewInstance performSelectorOnMainThread:@selector(createScreenTexture) withObject:nil waitUntilDone: YES];
 
+	// In case the client code tries to set up a non supported mode, we will
+	// fall back to CLUT8 and set the transaction error accordingly.
+	if (format && format->bytesPerPixel != 1 && *format != _videoContext->screenTexture.format) {
+		format = 0;
+		_gfxTransactionError = kTransactionFormatNotSupported;
+	}
+
 	if (!format || format->bytesPerPixel == 1) {
 		_framebuffer.create(width, height, Graphics::PixelFormat::createFormatCLUT8());
 	} else {
@@ -92,7 +99,6 @@ void OSystem_IPHONE::initSize(uint width, uint height, const Graphics::PixelForm
 		       format->rLoss, format->gLoss, format->bLoss, format->aLoss,
 		       format->rShift, format->gShift, format->bShift, format->aShift);
 #endif
-		assert(_videoContext->screenTexture.format == *format);
 		// We directly draw on the screen texture in hi-color mode. Thus
 		// we copy over its settings here and just replace the width and
 		// height to avoid any problems.
@@ -107,6 +113,7 @@ void OSystem_IPHONE::initSize(uint width, uint height, const Graphics::PixelForm
 }
 
 void OSystem_IPHONE::beginGFXTransaction() {
+	_gfxTransactionError = kTransactionSuccess;
 }
 
 OSystem::TransactionError OSystem_IPHONE::endGFXTransaction() {
@@ -114,8 +121,7 @@ OSystem::TransactionError OSystem_IPHONE::endGFXTransaction() {
 	updateOutputSurface();
 	[g_iPhoneViewInstance performSelectorOnMainThread:@selector(setGraphicsMode) withObject:nil waitUntilDone: YES];
 
-	// TODO: Can we return better error codes?
-	return kTransactionSuccess;
+	return _gfxTransactionError;
 }
 
 void OSystem_IPHONE::updateOutputSurface() {